Being organised in general has it's many benefits. It enables preparation of events foreseen in the future. This is applied to D&D as well. Having simple stuff such as pens, pencils, papers, rubbers, figurines, boards, laptop/computer and the manuals at the session will speed things up a bit without having to fumble around for a pencil to write the new health points down. Also an organised DM will attempt to break the paradox of preparing for the unprepared. This means an organised DM will be able to adapt to a sudden change in the party's direction, such as wanted to explore a nearby cave instead of continuing on with the main quest. The organised DM would have a list of NPC (non-playing-characters) names, shop names, names of locations, maps and spare figurines at hand. This is so he can improvise with previously organised material without wasting time thinking of new names and stumbling over what words to say.
Knowledge, it is our human nature to seek out and learn new things about our hobbies and the world around us. A good DM would be one who has learnt a lot about their edition of D&D such as spells, feats, monsters and equipment. This is to save time instead of looking though the players or dungeon master's guide to see what ability a monster has and making the other players wait around. It also gives off an aura of competence and knowing about D&D and therefore your players will respect and trust you more.
The ability to imagine other worlds, conjure up new cities, plots and legends. We all have imagination, this is what enabled us to be great scientists. We can all imagine strange beings and places by drawing and mixing our experiences together. A good DM would be able to have a good imagination to be able to create enchanting worlds that will draw the players in, or thinking up original quests that compels the player to keep going deeper into that dangerous cave.
Good writing ability
To be able to write up an adventure that anyone can follow. It get difficult when you make rough notes that misses out so many words you can't even remember what you were originally on about. This applies to describing an area the characters are in, there should be a good description of where the party is, what's it like and any key points in the area/room. This usually required a good writing ability.
Good verbal ability
A good crisp clear voice to communicate exactly, without ear straining, what the characters are doing and where they are. No one likes a mumbling DM with a monotonic voice. Change the tone of your voice every now and again to keep the players interested. If you can pull of accents, great, then go for it! It's more about not what you say but how you say it. That's why the same joke spoken by one person can be funnier compared to another person who explains the same joke but it doesn't seem as funny.
Any thoughts? Or comments? Any personal experience where you think you were a good DM?
Come back tomorrow for part two!